H DNA repair activity is linked with immune exclusion in pediatric kidney cancers Emily Higgs, BA, Ami Desai, MD, Riyue Bao, PhD, Thomas Gajewski, MD, PhD University of Chicago, Chicago, IL, USA Correspondence: Riyue Bao ([email protected]) EBI2/GPR183 list Journal for ImmunoTherapy of Cancer 2018, six(Suppl 1):P584 HSF1 Formulation Background A T-cell wealthy tumor microenvironment has been associated with improved clinical outcome and far better response to immune checkpoint blockade therapies in several adult cancers. Our group and other people have discovered mechanisms, including -catenin activation and PTEN loss, that drive a lack of T cell infiltration in tumor. Even so, a great deal significantly less is recognized concerning the tumor microenvironment in pediatric cancers, which harbor a reduced tumor mutational burden (TMB) than most adult cancers, as well because the molecular mechanisms responsible for driving T cell exclusion in these individuals. Thus, we analyzed pediatric kidney cancer data in the Therapeutically Applicable Investigation to Produce Efficient Treatments (TARGET) database. Methods RNAseq, somatic mutations, and clinical data were obtained for Wilms tumor (WT), rhabdoid tumor (RT), osteosarcoma (OS), and neuroblastoma (NBL) from TARGET, and adult kidney cancers from TCGA. Just after normalization and log2-transformation, we applied a 26-gene activated CD8 T cell signature  and identified anti- correlated genes at Pearson’s correlation r-0.20 and FDR-adjusted P0.05. Differentially expressed genes have been detected by ANOVA at FDR-adjusted P0.05 and fold modify 2.0. Association with progression-free survival (PFS) and all round survival (OS) was assessed using Mantel-Cox test. Results Among the 4 pediatric cancers, we observed the lowest activated CD8 scores in WT, only detected in tumor and not in matched regular. We identified 2,128 considerable genes negatively correlated using the score, 1,553 genes higher in WT compared to the adult kidney cancers, and 1,952 genes greater in WT than matched normals. There were 502 overlapping genes between these techniques. Pathway evaluation revealed the most activated pathways involve DNA repair. This was validated in RT. We then calculated a DNA repair expression score consisting of 4 genes (BRCA1, BRCA2, MSH2, MSH6). Inside the FHWT histology exactly where 90 from the individuals progressed, larger DNA repair score is associated with worse PFS (P=0.02), but not OS. Conclusions Our benefits showed that a higher DNA repair expression score is linked with decrease activated T cell gene expression in childhood kidney cancers including WT and RT, and is associated with worse survival. While loss of DNA repair pathways has previously been associated with elevated neoantigens and greater response to checkpoint blockade immunotherapy, our existing data recommend that upregulated DNA repair pathways may well create the opposite phenotype. Tactics targeting DNA repair pathways may very well be regarded as as new therapeutic interventions to transform non-T cell-inflamed pediatric tumors into clinically favorable tumors in spite of the low presence of somatic mutations.References 1. Charoentong, Pornpimol, Finotello F, Angelova M, Mayer C, Efremova M, Rieder D, Hackl H, Trajanoski Z. Pan-cancer immunogenomic analyses reveal genotype-immunophenotype relationships and predictors of response to checkpoint blockade. Cell Reports. 2017; 18:2482.Journal for ImmunoTherapy of Cancer 2018, six(Suppl 1):Web page 316 ofP585 Structured literature review and meta-analyses of your prevalence of microsatellite instability higher (.